Heat development of photographic plate containing volatile photosensitizer



Nov. 26, 1968 J. A. MATTOR ETAL 3,413,121

HEAT DEVELQPMENT 0F PHOTOGRAPHIC PLATE CONTAINING VOLATILE PHOTOSENSITIZER Filed March 29, 1967 Photographic Plate Comprising Plastic Film Conlaining lodoform Phol'osensilizer and Color-Farming Chemicols(e.g. a Furfurylidene and an Aromatic Amine) Expose Plale to Light Through a Negalive Develop Image by Heflfing to Above About lOO'G and Drive Phaloeensilizer From Background Areas 132032230319.- Joiaza H. Maiiiov, Lawfleuqe, Paine, a l I341,

United States Patent 3,413,121 HEAT DEVELOPMENT OF PHOTOGRAPHIC PLATE CONTAINING VOLATILE PHOTOSENSITIZER John Alan Mattor, Hollis, and Lawrence Price, Old

Orchard Beach, Maine, assignors, by mesne assignments, to Scott Paper Company, Delaware County, Pa., a corporation of Pennsylvania Continuation-impart of application Ser. No. 351,316, Mar. 12, 1964. This application Mar. 29, 1967, Ser. No. 626,881

4 Claims. (CI. 96-48) ABSTRACT OF THE DISCLOSURE A photographic film that contains color-forming chemicals that are activated by a lower haloalkane photosensitizer is developed by simply heating the plate, which simultaneously drives off the haloalkane in the background areas so that they are no longer photosensitive. Color-forming chemicals that can be used are the combination of an aromatic amine with (1) a furfurylidene or (2) a dioxane. The amine used is preferably one that will also volatilize during the heat development of the plate so that the background becomes more stable.

Related application This application is a continuation-in-part of Ser. No.

351,316, Photosensitive Medium Comprising a Furfurylidene, a Primary Aromatic Amine and a Lower Haloalkane, filed Mar. 12, 1964, by the present inventors and abandoned in favor of continuation-in-part application Ser. No. 641,720, filed Apr. 21, 1967.

Background of the invention This invention pertains to the field of photography and more particularly is concerned with a method of developing a photographic plate having a film containing dispersed therein color forming chemicals, that have been activated by a photosensitive lower-haloalkane, by heating the plate without any additional treatment.

The above identified applications, the disclosures of which are hereby incorporated by reference, disclose one combination of color-forming chemicals, a furfurylidene and a primary aromatic amine, that is particularly useful in the process of this invention. A lower haloalkane such as iodoform is used to sensitize the color-forming chemicals. It probably acts by liberating an acid when exposed to light, which acid acts on or activates the color-forming chemicals during the subsequent heat development.

This invention It now has been found that a photographic plate or film based on a resinous or polymeric film containing dispersed therein color-forming chemicals that are activated by a photosensitive lower haloalkane and subsequently developed by heat, the photosensitizer can be caused to volatilize from the unexposed background areas during the heat development so that the background areas are no longer photosensitive. This stabilization of the background areas is accomplished without the need of removing the resinous binders in these areas.

It will be apparent that this process is applicable to any photographic system that uses a lower haloalkane photosensitizer, alone or in the form of a complex, dispersed in a resinous film-forming binder.

It is preferred during the heatdevelopment to cause at least a major portion, if not all, of one of the colorforming chemicals to be driven off which helps to render the background area more stable, i.e., to reduce background degradation with time. When a primary aromatic amine is used as one of the color-forming chemicals, it can be so selected as to its volatility in a polymer binder at room temperature and at an elevated temperature in excess of about C. and up to 300 C. so as to achieve this result. It has been found that many of the primary aromatic amines are prone to autoxidation and that they are therefore desirably removed from the background during the development of the photographic plate. Generally speaking, it is preferred to use primary aromatic amines that are soluble in chloroform at 25 C. to the extent of at least 0.002 gr./ml.; and that have a boiling point in the range of 250 to 350 C. at 700 mm. Hg. The nature of the polymer binder will of course effect the relative volatility of the amine and thus its ability to be driven-off.

The drawing The drawing is a self-explanatory flow diagram of the process of this invention.

Preferred Embodiments A 30 pounds per ream (3300 sq. ft.) unfilled, lightly rosin sized carbonizing paper of uniform formation was impregnated via a Mayer bar with 5 pounds per ream of the following coating composition:

After drying in air, under a yellow safe light, the plate appeared translucent to the eye. It was contact exposed through a negative to light from a 1500 watt carbon are at a distance of 24 inches for 15 seconds. It was thereafter developed by heating to 150 C. for seconds in still air. An intense brown image was obtained. No chemical treatment was required to develop the image, to neutralize the background areas and/or to remove the background areas. The characteristic odor of iodoform had disappeared from the plate. Testing of the background areas by re-exposure under the same conditions without the negative caused no background discoloration. Analysis of the background areas by swabbing with an o-nitrobenzaldehyde, ethanol and chloroform solution followed by heating at C. indicated that substantially all of the aromatic amine had beendriven off. The photographic plate was exposed to sunlight in a window for 8 days without noticeable deterioration of the background.

A photographic plate is prepared from a coating solution consisting of 0.02 gram of S-brbmofurfurylidene azine (Compound VII); 0.06 gram 2,4-toluenediamine; 0.10 gram of iodoform; 0.2 gram of a polystyrene (Piccotex 120); 0.2 gram of another polystyrene (-PS3, The Dow Chemical Co.) and 4 ml. of chloroform applied to a cast coated paper in an amount of 4 pounds per ream (dry basis). The plate is exposed through a transparency using a 200 Watt tungsten lamp at a distance of 12 inches for 1 minute. Heat development at 300 F. for 90 seconds produces a blue image,

A moderately sized, unfilled, 28 pound per ream paper web is impregnated with 4 pounds per ream (dry basis) via Mayer bar application with the following formulation (parts by weight):

Formula II:

2-p-dimethylaminophenyl-5- (4-dimethylamino- 3 benzylidenefimino 1,3-dioxane (Compound II) g 0.04 1-chloro-2,4-phenylenediamine g 0.06 Iodoform g-.. 0.10 Polystyrene resin (Dow -PS-3) g 0.40 Chloroform ml 4.0

This plate yields a yellow image on white background when developed after exposure by heating to 175 C. in air for 30 seconds.

The following can be used in place of the above to produce plates that can be developed and stabilized with heat.

(Yields a deep brown image on white background; replace amine with 3,3-dimethoxybenzidene, to obtain a brilliant red image.)

Formula IV:

N-p-nitrophenyl-1,1,1,-trichloromethane sulfenamide (Compound IV) g 0.1 N,N'-diethylaniline g 0.1 Iodoform g 0.1 Polyvinyl butyral (Shawinigan Resins Butvar) 10 weight percent in acetone ml-. 4.0

(Yields blue image.)

Formula V:

N(p-tolyl)-1,1,1 trichloromethane sulfenamide (Compound V) g 0.2 Dimethylauiline g 0.1 Iodoform g 0.2 Polyphenylene oxide10 weight percent in chloroform ml 4.0

(Yields brilliant green image.)

Formula VI:

3,3,6,6-tetrachloro-2,3,5,6 tetrahydro-2,5 di ptolyl 1,4 dithia-LS diazine (Compound Polyvinyl butyral-10 weight percent in acetone ml 4.0

(Yields strong blue image.)

The film-forming plastic binder used should be essentially non-reactive with the other ingredients of the solution and desirably in the free state should form a translucent or transparent film when cast from a solvent solution that is colorless or substantially colorless, so as not to interfere or mask the color given by the colorformers. Some polyester polymers have been :found to be unsatisfactory and polymers containing large amounts of hydroxyl groups will usually interfere with image formations. The polymer should be unaffected by anhydrous hydrogen iodide at F. Besides the above resins, the hydrogenated polyterpenes, methyl methacrylates, styreneacrylics, polycarbonates, and colophouy are useful.

We claim:

1. A photographic process comprising (1) exposing an image receptive member which comprises a lightpassing binder containing in photographic amounts and proportions chemicals that interact after exposure and heating to produce a visible image, said chemicals comprising a color precursor selected from the group consisting of the furfurylidenes and dioxanes, a primary aromatic amine reactive with said precursor when activated and a lower haloalkane that is retained in said medium at ordinary ambient temperatures, and (2) developing an image on said member by heating said member to a temperature in excess of C. for a time sufficient to develop said image ,and render the background area photoinsensitive.

2. The photographic process of claim 1 wherein during said heating a substantial portion of said amine is driven from said background area along with substantially all of said lower haloalkane.

3. The process of claim 1 wherein said binder is carried as a thin film on a support.

4. The process of claim 1 wherein said binder is carried within the interstices of a thin paper web.

References Cited FOREIGN PATENTS 1,421,380 11/1965 France.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner. 

